This invention relates to ignition systems for spark ignited internal combustion engines, and deals more particularly with a module, for use in such a system, comprising a combined spark plug connector and ignition coil.
The module of this invention is intended for use with ignition systems of the well known type wherein high voltage pulses for firing an associated spark plug are produced by an ignition coil having a primary winding and a secondary winding, each high voltage pulse being produced as a result of a sudden change in the current flowing through the primary winding to induce the high voltage pulse in the secondary winding. In one form of such system, the current change in the primary winding is produced by a set of breaker points which first close to establish a current path through the primary winding and then open to interrupt such path. In another form of system, the current change in the primary winding is produced by suddenly discharging a condenser through such winding. The module may also be used with various different types of engines, but is particularly well adapted for use with relatively small single cylinder, distributorless engines of the type commonly used in chain saws, lawn mowers, snow blowers and the like.
In the past, it has been common to mount an ignition coil at some distance from the spark plug with which it is used and to connect the high voltage output of the coil to the plug by a heavily insulated conductor, the conductor often having a snap-fit connection at one end with the ignition coil at its other end carrying a spark plug cap adapted to fit over the outer end of the spark plug and to make electrical connection therewith. The use of such high tension conductors has several disadvantages, including breakage, loss of electrical energy in the conductor, safety hazard and expense; and, one of the objects of this invention is to eliminate the need for such a high tension conductor by locating the ignition coil directly adjacent the spark plug with which it is used.
As evidenced by prior U.S. Pat. No. 995,400, it is not unknown to combine an ignition coil with a spark plug connector. The arrangements provided in the past, however, have apparently not met with wide acceptance; and, another object of the invention is to provide a spark plug connector and ignition coil module which is an improvement over somewhat similar devices proposed in the past, the improvements residing, among other things, in simplified construction and mounting means. The mounting means for the module is such as to provide separate mounting of the module to parts other than the spark plug while also yielding a good water proof seal between the module and the spark plug and enabling easy removal and replacement of the module to gain access to the plug when necessary.